From the past, as a tuyere of a melting furnace used for melting ores or the like or a melting furnace such as a cupola, there is a structure in which a tuyere main body is set in a hole portion provided in a tuyere brick. The gap in the hole portion between the periphery of the tuyere main body and the brick wall is filled with a fire-resistant ramming material, so as to fix the tuyere main body as disclosed in Japanese Unexamined Patent Application, First Publication No. 2003-171706. The tuyere is used so that the blast of high-temperature gas is forced through the tuyere into a furnace, and the tuyere main body has a cylindrical or conic shape made of copper or a copper alloy.
Since the tuyere is exposed to an environment in which high-temperature molten metal or slag is dropped and a flame temperature in front of the tuyere is equal to or higher than 2000° C., wear and melting loss occurs, and this causes a significant reduction in the life of the tuyere. Accordingly, in order to extend the life of the tuyere, various measures for lengthening the life of the tuyere, including a tuyere structure in which the cooling chamber of the tuyere is separated, a tuyere structure in which an internal cooling water passage is formed into a spiral shape, a tuyere structure in which wear-resistant metal is implanted, a tuyere structure in which the front end portion thereof is subjected to hardfacing or the surface thereof is coated with a fire-resistant material, a tuyere structure coated with heat-resistant and wear-resistant fabric, and the like, have been proposed and employed,
In addition, the tuyere of a blast furnace adopts the structure in which the tuyere main body is disposed in the hole portion provided in the tuyere brick and the periphery (about 90 mm) of the tuyere main body is filled with a ramming material so as to be fixed. However, in case of the blast furnace, since the temperature in front of the tuyere is about 1100° C. and thus is low, melting loss of the ramming material is not observed, and it is sufficient that repair, replacement, and the like are needed only during regular furnace renovations of 10 to 20 years.
In addition, a melting furnace adopts a structure of lining fire-resistant material over an iron shell from a tuyere. However, there is a disadvantage in that when the applied fire-resistant material is damaged, the iron shell is exposed, and thermal insulation is deteriorated, resulting in an increase in heat loss.
On the other hand, with regard to the tuyere of the melting furnace, the flame temperature in front of the tuyere is equal to or higher than 2000° C. In the case where the ramming material is filled so as to be fixed like the cupola, wear and melting loss in the vicinity of the tuyere cannot be avoided, and frequent replacement and repair is needed for the tuyere and the vicinity thereof once in about 30 days. Moreover, when local melting loss occurs in the vicinity of the tuyere, the iron shell is exposed, and the thermal insulation is deteriorated, which causes a problem with an increase in operational load due to heat loss.
Under the circumstances, the development of a new tuyere structure capable of increasing the life of a tuyere is strongly required.